This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Application No. 2000-047309 filed on Feb. 24, 2000, the entire content of which is incorporated herein by reference.
This invention generally relates to a control device for controlling vehicle deceleration. More particularly, the present invention pertains to a vehicle deceleration controller that is adapted to provide a deceleration intended by the driver when an accelerator is released during driving.
Japanese Patent Laid-Open Publication No. H07-127720 discloses a speed change controller for an automatic vehicle transmission. The speed change controller automatically controls gear shifting by following a predetermined deceleration gear shifting pattern based on the shift position, the vehicle speed, and a value corresponding to the gradient of the road surface when the deceleration of the vehicle is detected (i.e., when the accelerator is released during driving). This brings about a deceleration effect through engine braking.
In this known speed change controller for automatic vehicle transmissions, the deceleration effect produced by engine braking and the required deceleration (i.e., the deceleration intended by the driver) when the accelerator is released do not always agree with each other. Thus, the deceleration obtained by the speed change controller may not satisfy the intent of the driver. Because the total vehicle weight, including the load, is not considered for speed control during deceleration in the aforementioned speed change controller, the optimal deceleration (i.e., the required deceleration) intended by the driver may not always be realized. That is because the deceleration by the engine brake obtained by the speed change controller varies depending on the total vehicle weight which varies depending on the load of the vehicle, particularly in case of a truck.
In light of the foregoing, a need exists for an improved vehicle deceleration controller that is not as susceptible to the shortcomings discussed above.
A need exists for a vehicle deceleration controller which is able to generally always satisfy the required or intended deceleration irrespective of changes in the vehicle speed, the gradient of the driving road, and the total vehicle weight.
In light of the foregoing, the present invention provides a vehicle deceleration controller that includes an accelerator condition detecting device that detects the vehicle accelerator condition, a vehicle detecting device that detects the vehicle speed, a road surface gradient detecting device that detects the gradient of the driving road, a vehicle weight detecting device that detects the total vehicle weight including the load of the vehicle, a braking force generating device that generates the braking force for braking the vehicle, and a judging device for judging the release of the accelerator based on the detected signal of the accelerator condition detecting device. A required deceleration memory device memorizes the required deceleration varying in accordance with the vehicle speed and the gradient of the driving road surface as a function of the vehicle speed and the gradient of the driving road surface, and a deceleration determining device determines the required deceleration in accordance with the driving road surface and the vehicle speed detected by the vehicle speed detecting device and the road surface gradient detecting device respectively while also referring to the memory of the required deceleration memory device. An operation mode memory device then memorizes the vehicle deceleration varying in accordance with the total vehicle weight, the vehicle speed, and an operation mode of the braking force generating device as a function of the operation mode, the vehicle speed, and the total vehicle weight, while an operation mode determining device determines the required operation mode in accordance with the required deceleration determined by the deceleration determining device and the vehicle speed and the total vehicle weight detected by the vehicle speed detecting device and the vehicle weight detecting device respectively while also referring to the memory of the operation mode memory device. An outputting mechanism then operates the braking force generating device with the required operation mode when the release of the accelerator is judged by the judging device. In this case, the braking force generating device includes an automatic transmission and an exhaust brake system.
In accordance with the vehicle deceleration controller of the present invention, when the accelerator is released during driving, the release of the accelerator is judged by the judging device based on the detected signal of the accelerator condition detecting device. Upon such judgment, the braking force generating device is operated with the required operation mode by the outputting mechanism.
The aforementioned required operation mode is determined in accordance with the required deceleration as well as the total vehicle weight and the vehicle speed detected by the vehicle weight detecting device and the vehicle speed detecting device respectively while also referring to the memory of the operation mode memory device memorized as a function of the vehicle speed and the total vehicle weight. The aforementioned required deceleration is determined in accordance with the vehicle speed and the gradient of the driving road surface detected by the vehicle speed detecting device and the road surface gradient detecting device respectively, while also referring to the memory of the required deceleration memory device memorizing the required deceleration that varies in accordance with a function of the vehicle speed and the gradient of the driving road surface.
Thus, with the vehicle deceleration controller of the present invention, when the accelerator is released during vehicle driving, the required deceleration in accordance with the vehicle speed and the gradient of the driving road surface can be obtained based on the magnitude of the total vehicle weight by the operation of the braking force generating device with the required operation mode. As a result, the vehicle deceleration obtained by the braking force generating device and the deceleration intended by the driver always agree with each other, thus satisfying the driver""s intent with respect to deceleration, even in the event of variations or changes in the vehicle speed, the gradient of the driving road surface and the total vehicle weight.
The vehicle deceleration controller of the present invention is also advantageous in that conventional devices such as the automatic transmission and the exhaust brake system can be adopted as the braking force generating device. Thus, implementation of the present invention does not entail a significant increase in manufacturing cost.